Automotive electrical systems are known to be particularly noisy. Even though power in an automotive system is ostensibly drawn from a battery, electrical transients are created by inductive devices that turn on and off as well as the charging system itself.
Voltage transients are well known to have widely varying slew rates. The amplitude of voltage transients can also be quite high. Transients having slew rates of 80,000 volts per second (100 microseconds rise time) and pulse durations of several milliseconds or more are not uncommon.
Those of ordinary skill in the art know that high slew rate, high-amplitude transients can wreak havoc on electrical devices used in automobiles and trucks, especially the semiconductors used in vehicle engine and vehicle fuel system control computers, air bags and other occupant restraint systems and vehicle entertainment systems, typical designs of which are well known to those of ordinary skill in the art and omitted for brevity. The power supply line for an integrated circuit has a distributed capacitance to ground. That distributed capacitance, and other lumped capacitances are electrically equivalent to short circuits during the occurrence of high frequency voltage transients. When they are applied to a capacitive load, the transients can cause currents to flow that can damage the capacitance, the source, as well as electrical devices connected between them.
A low pass filter can suppress high frequency transients but filters require bulky capacitors and inductors. An apparatus and method for effectively filtering high frequency, high voltage transients from capacitive loads would be an improvement in the prior art, especially if such an apparatus and method could be implemented in one or more semiconductor devices.